The ‘’’Gregorian Calendar’’’ (a.k.a. the “Catholic Calendar”) is the calendar which is now used throughout the world, and with which we are most familiar. There are other calendars in use, the Japanese Calendar, the Hebrew Calendar, etc. Introduced by Pope Gregory XVIII, this calendar corrected some of the difficulties which had arisen in using the Julian Calendar. While the calendar now bears his name, he didn’t make it himself, but instead appointed a commission of scholars to review all of the available data and come back with a conclusion which would best fit the science of the era.
"The Gregorian calendar was created by a group of nine scholars formed in 1582. One of these scholars was a deposed Patriarch of the Syriac Orthodox Church who fled to Rome after he resigned under pressure from Moslem over-lords and angry congregations in Mesopotamia. What seemed to be a humiliating fall from grace turned out to be a dramatic opportunity to participate in one of the great moments of European history. Ignatius Nemet Allah I served as Patriarch in Mardin (Turkey), seat of the Antiochian Patriarchate. He served for 19 years from 1557-1576 until he was forced to convert to Islam under threat of death. This conversion infuriated the Christian population and they demanded that their Patriarch resign. He did so and appointed his nephew to the position of Patriarch. He sailed to Venice.”"